Semiconductor chip packaging provides four major functions, that is, power input, signal communication, heat dissipation, and chip protection. The semiconductor chip is driven by external power supply to work. Through semiconductor chip packaging, the external power supply may stably supply power to drive the semiconductor chip to work. The semiconductor chip packaging also enables good signal communication, including the transmission of signals generated by the semiconductor chip and the receipt of signals transmitted to the semiconductor chip. Primarily, these functions are achieved through circuits disposed on a base plate on which the semiconductor chip packaging is carried.
The semiconductor chip will generate a large amount of heat during working or receiving signals transmitted thereto. With a heat transfer mechanism provided by the semiconductor chip package for efficiently dissipating the heat generated by the working system, the semiconductor chip is able to work at normal working temperature. However, in the event there are bubbles presented in the semiconductor chip package, the heat generated by the working system would lead to thermal expansion of moisture contained in the bubbles. The expanded bubbles will directly adversely affect the reliability and quality of the product. Therefore, it is always an important issue in the semiconductor industry to remove bubbles from the semiconductor chip package.
In the conventional semiconductor chip packaging process, a wafer is first cut into chips of required sizes, and then, the chips are attached to the base. In the process of applying or curing the adhesive material, bubbles would present in the adhesive material, at an interface between the adhesive material and the base, and at an interface between the adhesive material and the chip. These bubbles result in a plurality of voids in the adhesive material when the latter is cured, and inevitably adversely affect the reliability, the quality, and even the functions of the product.
According to a first conventional method, the bubbles in the adhesive layer are expelled by applying high temperature and high pressure in the process of resin molding for a short period of time. In a second conventional method, the bubbles in the adhesive layer are removed by a vacuuming process. In a third conventional method, the process parameters of the chip implanting machine and other related manufacturing facilities are adjusted to avoid the generation of bubbles at the interface between the chip and the adhesive material.
However, all the above-mentioned conventional methods have some disadvantages. For example, according to the first conventional method, to remove the bubbles from the adhesive material by applying high temperature and high pressure in the process of resin molding for a short period of time, the adhesive material must become cured or at least become cured to a certain degree. This requirement would narrow the conditions for the semiconductor chip packaging process. Moreover, this method has limited effect with respect to chips having relatively large areas because the high temperature and high pressure exist only for a short period of time.
In the case of removing the bubbles in the adhesive layer by vacuuming process, the adhesive material is generally limited to that in the form of paste instead of film. Therefore, the vacuuming process has a very limited range of application. In addition, the bubble removing effect of the vacuuming process is easily affected by the type of material. Therefore, the vacuuming process also narrows the conditions for the semiconductor chip packing process.
In the above-mentioned third method for avoiding bubbles and eliminating voids in the adhesive material, some parameters for the chip implanting machine, such as chip temperature, chip-implanting pressure, and pressure dwell, are adjusted. However, to reach the required wetness at the adhering interface during the chip implantation, it is often needed to raise the chip temperature and increase the chip-implanting pressure and the pressure dwell.
However, all these adjustments tend to adversely affect the chip quality or lead to reduced production efficiency. Moreover, these adjustments are useless to the bubbles presented in the adhesive material. In addition, the effect of these adjustments reduces with increase in the chip size.